How Resource Capping Works

The daemon repeatedly samples the resource utilization of projects that
have physical memory caps. The sampling interval used by the daemon is specified
by the administrator. See Determining Sample Intervals for additional information. When the system's physical memory
utilization exceeds the threshold for cap enforcement, and other conditions
are met, the daemon takes action to reduce the resource consumption of projects
with memory caps to levels at or below the caps.

The virtual memory system divides physical memory into segments known
as pages. Pages are the fundamental unit of physical memory in the Solaris
memory management subsystem. To read data from a file into memory, the virtual
memory system reads in one page at a time, or pages in a
file. To reduce resource consumption, the daemon can page out,
or relocate, infrequently used pages to a swap device, which is an area outside
of physical memory.

The daemon manages physical memory by regulating the size of a project
workload's resident set relative to the size of its working set. The resident
set is the set of pages that are resident in physical memory. The working
set is the set of pages that the workload actively uses during its processing
cycle. The working set changes over time, depending on the process's mode
of operation and the type of data being processed. Ideally, every workload
has access to enough physical memory to enable its working set to remain resident.
However, the working set can also include the use of secondary disk storage
to hold the memory that does not fit in physical memory.